Lightning arrester



Sept. 23 1924.

G. M. LITTLE LIGHTNING AQRRESTER Filed July 13, 1922 2 Sheets-Sheet 1 INVENTOR George M Little BY ATTORNEY WITNESSES:

Sept; 23, 1924. 1,509,514

" G. M. LITTLE LIGHTNING ARRESTER Filed July 13, 1922 2 Sheets-Sheet 2 Pigs.

WITNESSES: INVENTOR Geovge I"1 Lime. BY

Patented Sept. 23, 1924.

1,509,514 UNITED STATES PATENT/OFFICE.

GEORGE Ill/I. LITTLE, Oi PITTSBURGH, PENNSYLVANIA, ASSIGNOR 'IO WESTINGHOUSE ELECTRIC &; MANUFACTURING COMPANY,A CORPORATION 01E PENNSYLVANIA.

LIGHTNING ARRESTER.

Application filed July 13, 1922. Serial No. 574,762.

To all whom it may concern:

Be it known that I, GEORGE M. LI'ITLE,

a citizen of the United States, and a resident of Pittsburgh, inthe county of Allegheny and State'of Pennsylvania, have invented a new-and usefullmprovement in Lightning Arresters, of which the followmg is a specification.

This invention relates to resistor materials, more particularly to plates of high-' resistance material adapted for use in lightstructure-are utilized toconnect the same in a suitable electrical circuit to be protected.

"Owing to the high resistance of the material, substantially no current passes therethrough at the normal operating voltage of the circuit to' be protected, but, upon the application thereto of a high abnormal voltage, such as a lightning discharge,- the gaps between adjacent contacting plates break down, initiating a glow discharge which.

spreads uniformly over the surfaces of the plates, thus providing a discharge path for the abnormal voltage. The outstanding characteristic of the glow-discharge arrcster of the above-mentioned application is that the discharge is interrupted when the volt age falls to a value but slightly below the breakdown voltage.

It has been found that, in some cases, the

power current tends to flow through the lightning arrester after the abnormal volt age has been discharged. This, in a measure, occurs because of fine particles of material which tend to bridge the small gaps between the plates and to the resistance of thelates which must not be so high as to unduy limit'the discharge capacity of the lightning arrester.

To obviate this disadvantage, the plates' have been provided with integral ribs of high-resistance material in order that the plates may, make contact at a relatively small number of points of high resistance and, therefore, prevent the power current from flowing after the lightning discharge has passed through the arrester. Genersistance material than the body, this being accomplished by oxidizingthem by contact with a heated plate. This improvement is described and claimed in the co' pending application ofJ. Slepian for disk structure, filed February 16, 1922 Serial ho. 536,910 and assigned to the W. E.& M.

It has been found desirable, in this type of lightning arrester, to have the plates of higlrresistance material of large size in or der that the discharge capacity of the lightning arrester may be increased. It is, therefore, an object of the present invention to provide a plate structure which shall be adapted to manufacture in large sizes and which shall be simple in construction and efiicient in operation.

In practising my invention, I provide a comparatively large plate or disk 'havin a plurality of ribs thereon, the distance between adjacent ribs being small, as compared with the lar est dimension of the plate or disk. By t e provision of sucha structure, I obtain a plate having a comparatively large number of points along which discharge may begin and thereby cause the same to spread rapidly and uniformly over the entire surface thereof. The efiiciency of the lightning arrester is thereby increased and the discharge of abnormal voltage is thereby accelerated. i

In the accompanying drawings constitu ting apart hereof and'in which like reference characters indicate like parts,

ally, the ribs have been made of higher re- Fig. l is a' plan view of a plate made, in

accordance with my invention;

Fig. 2 is a cross-sectional view thereof taken along the line II-II ofFig. 1, showing a stack of such plates;

Figs. 3 and 4.- are plan views of slightly modified forms of my invention;

Figs. 5 and 6 are plan and cross-sectional views, respectively, of a still further modification thereof, and

Figs. Y and 8 are similar views of a some what different form thereof.

The disk or plate 1, which may be made of kaolin, carborundum and graphite is provided with parallel ribs 2 having intermediate portions 3 therebetween, said portions being small relative to the diameter of the disk. Preferably theribs 2 are of higherresistanee' material than the body portion and may be obtained by placing the surfaceof the platein contact with a heated surface which-oxidizes the rib portions, removing a portion of the carbon therefrom and increas= i g the resistance thereof to any desired degree.

In Fig. 3 I have shown a similar structure comprising two sets of ribs 4: and 5, the ribs of each set being parallel ,to each other and the sets being arranged at ,right angles.

Spaces 6 constitute the depressed portions between adjacent and intersecting ribs. In Fig. 4 I have shown a disk structure having concentric ribs7 and intermediate depressed mediate portions 10 therebetween. An openportions 8 therebetween.

In the embodiments shown in Figs. 3 and 4:, it may be difiicult to satisfactorily burn out the carbon uniformly over the entire surface of the plate because of the inability of oxygen from the air to penetrate to the interior during the heating operation. I, therefore, provide a structure, as shown in Fi s. 5 and 6, in which the disk 1 is provided with concentric ribs 9 having intering 11 is provided centrally of the disk in order that, when said diskis placed upon a hot-surface in order to oxidize the ribs, oxygen may have access thereto, both fromthe outside of the disk 1 and through the opening 11 therein.

Another structure which has the desirable characteristics of those described above con sists of a rectangular plate 1 (Figs. 7 and 82, the len th thereof being considerab y greater t an the width, which is provided with ribs 12 and 13 along the sides thereof, leaving the central plate, a discharge, starting adjacent to the shown herein,the ribs are uniformly spaced in regular patterns but I am not limited to r such spacing since irregular spacing of the ribs will give substantially the result above set forth.v These and other changes may be made in the details of construction of my plate, my invention being limited only b the claims appended hereto.

I claim as my invention: 1. A plate of high-resistance material comportion 14 depressed. By reason of the proximity of ribs 12 to each other, as compared with the length of the a plurality of ribs thereon, the distance between adjacent ribs-being substantially less than the largest dimension of said plate, the resistance of said ribs being higher than that of the body portion.

2. An excess-voltage protective device comprising at least one pair of juxtaposed plates, and a plurality of high-resistance spacing means interposed between said plates, the distance between said spacing means being substantially less than the largest dimension of said plates, and the resistivity .and spacing being such that the protectiy e device permits a relatively large current-flow at voltages above a predetermined value and prevents any subs Llltlll current-flow at voltages below said value.

3. An excess-voltage protective device comprising at least one pair of juxtaposed high-resistance plates having a discharge gap therebetween, and a plurality of highresistance spacing means interposed between said plates, the distance between said spacing means being substantially less than the largest dimension of said plates.

4;. A protective device comprising at least one pair of juxtaposed high-resistance plates, and a plurality of high-resistance spacing means interposed between said plates, the distance between said spacing means being substantially less than the largest dimension of said plates, the specific resistance of said spacing. means bein higher than the specific resistance of sai plates.

5. An excess-voltage protective device comprising at least one pair of juxta sed high-resistance plates having a disc arge gap'therebetween, at least one of said plates having a plurality of integral ribs contactr ing with the other plate, the distance between said spacing ribs being substantially less than the largest dimension of said plates.

6. An excess-voltage protective device comprising at least one pair of juxtaposed high-resistance plates having a discharge gap therebetween, at least one of said plates having a plurality of integral ribs of increased specifie' resistance contacting with the other plate, the distance between said spacing ribs being substantiall. than the largest dimension of said plal es 'Z. A. space-current dischar e device comprising at least one pair of e ectrode plates having a discharge gap therebetween, one of said plates carrying a plurality of ribs contacting with the other plate for spacing the same, the distance between said spacing ribs being substantially less-than the largest dimension of said plates.

8 A space-current dischar e device comprising at least one pair of e ectrode plates having a discharge gap therebetween, the

prising a substantially flat body portion and material of at least one of said plates having comprising at least one pair of juxtaposed plates, and a plurality of high-resistance spacing means interposed between said plates, the distance between said spacing means being substantially less than the largest dimension of said plates, and the spacing being such that the space-current flow between the plates always takes the form of a glow discharge.

10. An excess-voltage protective device comprising at least one pair of juxtaposed high-resistance plates, and a plurality of higlrresistance spacin means interposed between said plates, t e distance between said spacing means being, substantially less than thelargest dimension of said. plates,

and the resistivity and spacing being such that the protective device permits a relatively large current-flow at voltages above a predetermined value and prevents any substantial current-flow at voltages below said value.

11. A space-current discharge device oom- 1prising at least one pair of electrode plates aving a discharge gap therebetween, one of said plates carrymg a plurality of ribs contacting with the other plate for spacing the same, the distance between said spacing ribs being substantially less than the largest dimension of said plates, the organization being such as to cause a glow discharge at voltages above a predetermined value and to permit no space-current discharge at voltages materially below said value.

In testimony whereof, I have hereunto subscribed my name this 11th day of July 1922.

GEORGE M. LITTLE. 

